1)
Why did they not mention the donkey?
1.
Malbim: They did not see the donkey. It was on [the other] side, like Targum Yonasan 'Ka'im l'Kablei.' They saw a great Chidush 1 . [Normally,] a lion does not kill and leave the carcass! (It kills only when it wants to eat.)
1
Had they seen also the donkey, also this was a great Chidush, that it does not flee from the lion! (PF)
2)
How did they know to tell about this in the city of the elder?
1.
Malbim: This was Hashgachah, in order that the elder would bury him honorably, and his grave would be a remembrance at the end of days (Melachim II, 23:17).
